System of electric distribution



v(No Model.) 2 Sheets-Sheet. 1.

. B. W. RICE, Jr.

SYSTEM OF ELEUTRIU DISTRIBUTION- N0. 516,83\5. Patented-Mar. 20, 1894.

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I (No Model.) 2 Sheets-Sheet; 2.

i E. W. RICE, Jr.

SYSTEM OF ELECTRIC DISTRIBUTION. No. 516,835 1 Patented Mar. 20', 1894.

UNITED STATES PATENT OFFICE.

EDWIN W. RICE, JR., OF SWAMPSCOTT, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF BOSTON, MASSACHUSETTS.

SYSTEM OF ELECTRIC DISTRIBUTION.

- SPECIFICATION forming part of Letters Patent No. 516,835, dated March 20, 1894.

I Application filed March 6, 1893- Serial No. 464,687- (No model.)

systems of distribution, and has for its obect to provide an economical method of distr buting current to a circuit or net-work of wires, where it is desirable to keep the potential equal or approximately equal throughout the whole distance covered thereby.

It has been customary heretofore to supply all parts of such net-work of wires by a system of feeders having a common source of electricity, they being all supplied at the same potential. But under increase of load such a system involves a very greatdrop of potential in the feeders going to the distant points of the circuits and the translation devlces, such as electric motors or lights, can not be run satisfactorily. To avoid this difficulty various plans have been proposed; first, resistances have been introduced in the feeder circuits and varied in correspondence w1th the conditions of load; second, separate machines have been connected to the longer feeders, such machines being shunt wound and a variation of resistance in the shunt winding being made to increase the potential of the generated current to compensate for the fall in voltage; third, it has also been proposed to maintain the current from the group of generators at the power station at approximately constant potential or to raise and lower the potential of all the machines together, and out in and out feeders running to the difierent parts of the circuit in such manner as to prevent undue drop of potential in the heavily loaded parts of the system, more feeders being included in circuit to such parts and some of the feeders to the lightly loaded parts being disconnected to prevent too great a rise of potential; and fourth, it has likewise been proposed to insert a series wound. generator in each feeder which will vary the potential of the delivered current in correspondence to the load. All of these methods are open to objection, the first on account of the difiiculty in obtaining proper regulation and the waste of current in the resistances; the second, because of the expense of using so many machines; third, because it involves a Waste of energy by the insufficient amount of copper for light loads, and the fourth involves the multiplicity of small and uneconomical motors and generators. In my present invention I overcome these difficulties and secure a feeder system of distribution which is self-regulating and which requires the least possible number of machines, because thefeeders are permanently adjusted to the demands of the sections of the system for which they are designed, and an increased load or demand is supplied automatically from large generators by an increase in the initial or dynamo pressure, Without resorting to the use of resistances or a decrease in'the number of feeders, which is equivalent to an increase of feeder resistance, and without unduly multiplying the number-of machines.

In the accompanying drawings hereby referred to and. made part of this specification,

like letters refer to like parts, and therein Figure 1 shows a diagrammatic and conventional representation of an arrangement embodying myinvention, while Fig. 2 represents a modification of the arrangement shown in Fig. 1.

G, G, G are compound-wound dynamos connected in multiple to the bus-bars 0,0 and having the series coils connected as is customary by the wire E. Each dynamo is provided with an ordinary regulator or controller, R, and an adjustable resistance, R, to vary the absolute potential as may be required. From the bus-bars feeders a b are conducted to the different portions of the mains P W supplying the motors M M, &c.; the feeders a b, &c., represent those furnishing the principal current requirements of the mains, while'such parts of the circuit as require current of a greater electro-motive force to be supplied to them in order to prevent undue drop in voltage, are supplied by the means further hereinafter described.

To supply the portions of the circuits at a greater distance from the power-station I provide another generator, as G or two generators, G G", which may or may not be connected in multiple, as may be desired. The feeders, c, d, e, f, leading to the portions of the mains P WV supplied by these generators have a drop of potential under load greater than that of the feeders from the generators G, G, G and the generators G G are therefore over-compounded as compared with the machines G, G, G that is, the potential of the current at the brushes of G and G rises more rapidly with access of load than is the case with the generators G, G G Where any portion of the mains is very near the power-house, I may provide a separate generator, as G which will be simply a compound-wound machine, that is, regulated for constant potential, irrespective of load, to supply such portions of the circuit.

It is to be understood that the other generators herein described are over-compounded and that their compounding is proportioned to the drop on the feeders which they supply. To keep watch of this potential return wires may be run to the station and indicating devices inserted therein in any usual or customary manner.

In the modification illustrated by Fig. 2, the generators for supplying the distant portions of the circuit are represented by G G and G G; and are somewhat differently arranged from those shown in Fig 1. G represents an ordinary shunt-wound dynamo; while G represents a series dynamo connected thereto, by which the over-compounding is efiected, substantially in the same manner as would be done in the series coil as shown in Fig. 1. The generators G G are arranged in a similar manner.

The operation of my improved system is as follows: Supposing the car to start at the left hand lower side of Fig. 1,in passing near the power house its current requirements will be supplied by the main current source consisting of the generators G, G, G and in addition by the generator G Should any block occur in the road, and a number of cars be collected near the source of current, when the cars start and the demand for current becomes very great, the ordinary compounding of the generators in the main bank will be suflicient to supply the demand through the feeders of least length and resistance. The cars then proceeding along the railway will become distributed and the necessary current will be supplied in part by the feeders c, (1, leading from the generator G and as the cars become distributed more and more equally along the track, all of the generators will be brought into operation, and the current requirements will be substantially uniform; during the existence of this condition or during ordinary demands for current extending over all parts of the line, the generators G and G may be switched in with the main bank of generators and connected to the bus-bars, as the current supplied by them will be of substantially the same potential as that furnished by the generators G, G, G Should such a block as I have described occur upon the portion of the railway to the right in Fig. 1, the principal demand for current will be supplied by the generator G which is over-compounded to furnish a higher potential under load than the other generators forming the main source of current supply, because the resistance of the feeders c, d is necessarily greater than that of the shorter feeders, a, b, &c. At such times the generators G G would preferably be disconnected from the bus-bars, because the difierence of potential between the different units would be too greatand the higher potential current delivered by these generators might even tend to drive the others in circuit as motors.

The operation has been described with reference to a railway line, but it will be readily understood that it is the same where other translating devices than motors are employed, as for lights, incandescent or arc, which may be switched in; as for instance, where the difference is between a residence section and a business section supplied from the same common source,where the maximum load in the business section will come early in the evening, but as business ceases, the residence section will take more current as people go to their homes, thus transferring from one part of the system to the other the maximum load. All such variations of load will be readily taken care of by the combinations of generators which I have described herein.

I have shown in the drawings the mains embracing a number of motors, but it is evident that the principles of my invention may be as well applied to any other form of translating device as to the motor shown.

This modification is not the preferred form of my invention, as it introduces the objectionable element of small machines; but it differs from any other system known to me in which extra small machines are employed, in that in my system they only serve to give to certain large generators feeding different parts of the system the efiect of the usual over compounding field coil, whereas previous plans contemplated for each large generator a multiplicity of smallgenerators in the respective feeders leading therefrom in order to differentiate the pressure in the several feeders from one machine. My system thus avoids multiplying the feeders and small machines.

Having thus described my invention, what I claim is- 1. The combination in a system of electrical distribution of a set of electric generators one or more of which are compound-wound and adapted to maintain constant potential of the generated current, some of which are compound-wound to give a certain increase of potential of the generated current, and others of which are compound-wound to give a still greater increase of potential, with access of load or demand for current, and feeder hues connecting the respective generators to the work circuit, said generators organized to maintain approximately constant potential at the junction of the feeder lines with the work circuit.

2. In a system of electrical distribution, a work circuit extending over a considerable area, an electric current-source supplying currents of approximately constant potential, an electric current-source supplying currents of increasing potential with increase of current, an electric current-source supplying currents of still greater increase of potential with increase of current, and feeder lines connecting the said sources to the work circuit, said generators and lines proportioned to maintain an approximately constant potential between the mains of the work circuit.

3. In a system of electric distribution, a work circuit covering an extended area, a set of feeders supplying the bulk of the demand for current connecting said work circuit with a current source adapted to deliver currents of augmented potential with increase 'of current, and an auxiliary feeder, or set of feed ers, of greater length than those of the main set, connecting the work circuit to a separate current source, said latter source adapted to furnish currents whose potential rises in greater ratio to increase of current than'that from the main source.

4. In a system of electric distribution, one or more over-compounded electric generators feeding one portion of the system through a feeder or set of feeders, and one or more over-compounded electric generators feeding another portion of the system through a feeder or set of feeders, the latter machine or machines adapted to increase the potential of the delivered current, with access of load, more rapidly than the former.

5. In a system-of electric distribution, a constant potential generator connected directly to the mains, in combination with overcompounded generators connected to the remoter portions thereof by independent groups of feeders, the compounding efiect of the generators connected to each group of feeders being suitably proportioned to compensate for the drop of potential of current flowing therethrough.

6. In a system of electrical distribution, over-compounded electric generators, G, G,

G feeding work circuit P W, and adapted to their junction with the work circuit during change of load.

7. In a system of distribution of electric energy, over-compounded generators, as G, G, G and G G &c., supplying difierent portions of a main, as P W, by groups of feeders, as a b, 0 cl, cf, in combination with a generator of current of approximately constant potential, as G connected immediately to the mains, substantially as described and set forth herein.

8. In asystem of distribution of electric energy, compound-wound dynamos connected in multiple through bus-bars to groups of feeders supplying the principal current requirements of the line, in combination with other over-compounded current-sources of a higher potential supplying the distant portions of the circuit through independent groups of feeders, substantially as described.

9. In a system of distribution of electrical energy, compound-wound dynamos connected in multiple through bus-bars to groups of feeders supplying the principal current requirements of the line, in combination with other current-sources of higher potential supplying the distant portions of the circuit through independent groups of feeders, and a generator of approximately constant potential, as G connected near to the lines, Whereby the potential is. maintained, substantially uniform throughout the work circuit, substantially as described and set forth herein.

10. In a system of electrical distribution, a

number of dynamo generators supplying the generator group or unit, and means for increasing the potential of the generated current in each group in correspondence with the conditions of load so as to maintain a constant potential at the point of connection of the feeder and work circuits.

11. In a system of electric distribution, the method of maintaining uniformity of potential throughout an extended work circuit, consisting in generating currents whose potential increases at a predetermined rate with increased load, and currents whose potential increases'at a greater rate with increase of load, and conveying all of the said currents to the work circuit through feeders proportioned to the character of the supplied current.

In witness whereof I hereunto set my hand this 3d day of March, 1893.

EDWIN W. RICE, JR. Witnesses:

JOHN W. GIBBONEY, JOHN T. BRODERIOK. 

